The present invention relates to the laying of cables in sewers, and in particular to a means for enabling such cables to be laid along the flow channel at the bottom of a sewer.
In order to install a new hardwired network, it is necessary to provide cables linking the various nodes in the network. Often, this will require the cables to link nodes at one address with nodes at one or more different addresses. In order to minimise disruption caused by the laying of new cables, some network installers have taken to laying cables within sewer pipes rather than constructing dedicated conduits. This provides a convenient path for the cable that is relatively sheltered and can cost less than providing a dedicated conduit. Furthermore, providing a dedicated conduit would typically involve digging a trench for the conduit and filling the trench after installing the conduit, which causes considerable disruption to others, particularly if the cable is to be laid in an urban area.
When laying cables within a sewer, the cheapest and simplest solution is to lay the cables along the flow channel at the bottom of the sewer. A cable lying parallel to the direction of flow in the flow channel has a minor to negligible effect on the flow rate and a similarly minor likelihood of snagging debris and thus blocking of the flow channel. At some point however, the cable must enter/exit the flow channel. At such points, the cable lies across the direction of flow and thus creates a significant barrier to flow and a greatly increased chance of causing a blockage. Accordingly, sewer operators are reluctant to allow cables to be laid in this manner.
An alternative solution has been to pin the cable to the roof of the sewer. This avoids the potential for blockage, however, this solution is considerably more expensive than laying the cable along the flow channel and is often more expensive than preparing a dedicated cable conduit.
It is therefore an object of the present invention to enable a cable to be laid in a sewer in such a manner that alleviates or overcomes the above problems.
According to a first aspect of the present invention there is provided a cable guide, suitable for enabling a cable lying in the flow channel of a sewer to traverse and exit the flow channel without substantially impeding the flow, the cable guide comprising: a body section adapted to lie substantially flush with the wall of the flow channel; and an arm section projecting from the body section, the arm section having a distal end positioned outside the flow channel when the body section lies flush with the flow channel wherein the arm section provides a passage suitable for carrying a cable, the passage extending between an opening provided in the body section and an opening provided at the distal end of the arm section.
The passage in the cable guide above thus provides a means by which a cable can traverse the flow channel with minimal disturbance to the flow.
The cable guide may be formed from Polyvinyl Chloride, Polypropylene, Glass Reinforced Plastic, stainless steel or any other material suitable for resisting decomposition by chemical or biological agents likely to be present within the sewer effluents such as oils, acids and other substances.
The body section may be adapted to lie substantially flush with: one wall of the flow channel; one wall of the flow channel and at least part of the base of the flow channel; or both walls of the flow channel and the base of the flow channel. In order that the body section may lie substantially flush with the wall of the flow channel, one face of the body section may be shaped to correspond with the wall of the flow channel. In some embodiments, the body may be shaped so as to lie within a recess provided in the wall of the flow channel.
A second face of the body section forms a boundary to the flow channel. The second face may be shaped and/or otherwise adapted to minimise disturbance of the flow. The opening provided on the body section may be provided on the second face.
The cable may run across the second face of the body to the opening. In such embodiments, in order to ensure that the cable enters the opening at an angle that will minimise impedance of the flow, one or more cable clips may be provided. The or each clip may be provided on the second face of the body section. In such embodiments, the clips may be formed integrally with the body portion. Additionally or alternatively, one or more cable clips may be provided directly on the walls or base of the flow channel. Preferably, one cable clip is provided adjacent to the opening provided in the second face of the body section. In one preferred embodiment, the or each clip comprises a pair of resilient jaws adapted to retain a cable pushed into a position between the jaws. Additionally, to further secure the retention of the cable, a locking element may be provided, the locking element adapted, in use, to wrap over the cable and enclose the cable within the clip. Preferably, the clip (and in such embodiments the locking element) will be formed from stainless steel.
Alternatively, the opening may be provided at or towards the periphery of the second face and the cable may run behind the second face. In such embodiments, the cable may run in an extension of the passageway between the first and second faces. In an alternative to this arrangement, the cable may run across the first face of the body to enter the passageway. In order to maintain the substantially flush relationship between the body section and the wall of the flow channel, either or both may be provided with a recessed channel along which the cable may run.
The arm section may be provided in a fixed relationship to the body portion. Alternatively, the arm section may be adapted such that its orientation relative to the body portion may be varied and/or such that it may be bent into an advantageous shape or position. Similarly, the body section may be adapted to be bent into an advantageous shape. This will allow the cable guide to be adapted to local variations in the size and/or shape of the flow channel.
The arm section may be adapted to minimise disturbance to any flow outside the flow channel. Such additional flows may occur during peak usage or due to dissipation of heavy rainfall. To achieve this, the arm section may have a lower face adapted to lie flush with the sewer. Additionally, the arm section may have an upper face shaped and/or otherwise adapted to minimise disturbance of the flow.
The arm section and/or the body portion may be retained in position by use of a suitable adhesive, such as an epoxy resin or similar. Preferably, the adhesive is adapted to cure within a time period of say, 1 hour or less. Most preferably, the adhesive is adapted to cure within a time period of say, 15 minutes or less. Advantageously, the adhesive is adapted to cure in the presence of water. Alternatively, the body section may be secured in position by means of suitable fixing means. The suitable fixing means may comprise bolts, screws, nails or similar driven into the wall of the flow channel through fixing holes provided in the body.
In some embodiments, the arm section may be adapted to lie in a pre-existing or specifically prepared groove or recess in the sewer. In such embodiments, the arm section may be retained in the groove or recess by adhesive or any other suitable means. Preferably, in such embodiments, the arm section and/or body portion substantially fills the groove or recess, such that a smooth flow may be achieved. If the arm section and/or body portion does not fill the groove or recess, then a suitable filler material may be used to fill and/or smooth over the groove or recess.
In one preferred embodiment, the body section comprises a panel shaped to conform to the profile of the flow channel and the arm section comprises a tube projecting from the face of the body section adapted to conform to the profile of the flow channel.
According to a second aspect of the present invention there is provided a network comprising: one or more cables laid along the flow channels of sewers; and one or more cable guides according to the first aspect of the present invention.
The network of the second aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention as desired or as appropriate.
Preferably, a cable guide according to the first aspect of the present invention is provided at each point where a cable is required to enter/exit the flow channel of a sewer. The cable guides may be provided on either side of bends and/or junctions in the sewer and at places wherein the cable is to exit the sewer altogether. At such points the cable may be pinned to the walls or roof of the sewer once it exits the flow channel. Additionally or alternatively, the cable may be passed into a bypass tube or duct or into an exit duct once it exits the flow channel. Where the cable exits the sewer, the exit point of the cable from the sewer may be sealed around the cable to inhibit the escape of noxious or unpleasant gases.
The network can be used for any data. The cables within the network may be adapted to early electrical or optical data signals and may thus be electrical data cables or fibre optic cables as required.
According to a third aspect of the present invention there is provided a method of laying a cable network incorporating at least one cable lying in the flow channel of a sewer comprising the steps of: laying a cable in the flow channel of a sewer; installing a cable guide according to the first aspect of the present invention at points wherein the cable is required to enter/exit the flow channel; and passing the cable through the cable guide.
The method of the third aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention or the network of the second aspect of the present invention as desired or as appropriate.
In embodiments wherein a clip is provided, the method may include the additional step of fixing the cable in position using the clip.
The method may involve providing for the cable to leave the flow channel on either side of bends and/or junctions in the sewer and at places wherein the cable is to exit the sewer altogether. At such points the method may involve pinning the cable to the walls or roof of the sewer once it exits the flow channel. Additionally or alternatively, the method may involve passing the cable into a bypass tube or duct or into an exit duct once it exits the flow channel. Where the cable exits the sewer, the method may involve sealing the exit point of the cable from the sewer around the cable to inhibit the escape of noxious or unpleasant gases.
According to fourth aspect of the present invention there is provided a method of installing a cable guide in accordance with the first aspect of the present invention in the flow channel of a sewer comprising the steps of: applying adhesive to the cable guide; and positioning the cable guide at a desired location in the flow channel of a sewer.
The method of the fourth aspect of the present invention may incorporate any or all of the features described in relation to the cable guide of the first aspect of the invention, the network of the second aspect of the present invention or the method of the third aspect of the present invention as desired or as appropriate.
In relation to some embodiments, the method may incorporate the step of providing a groove or recess for the arm section and/or the body portion. The groove or recess may be formed by use of a disc cutter. This can enable the convenient formation of a groove or recess of pre-determined width and depth. In such embodiments, the method may comprise the further step of applying filler material over the arm section or body portion to provide a smooth surface.
Preferably, the filler material is of sufficient viscosity to substantially hold its shape whilst curing thus allowing the groove or recess to be filled. Advantageously, the filler material is adapted to cure in the presence of water. The filler material may be an epoxy resin. If an epoxy resin adhesive is used to retain either the arm portion or the body portion in position, the filler material may be the same epoxy resin.